Three hundred ten aneroid and 25 mercury sphygmomanometers in hospital use were calibrated against a new mercury manometer standard which properly recorded zero. A total of 68.4% (212 of 310) of the aneroid instruments and all of the mercury instruments were accurate within ± 3 mm Hg tolerance (average of four readings). An average deviation from standard of greater than ± 7 mm Hg was shown by 13.2% (41 of 310) of the aneroid instruments. Significant variation among hospitals in the proportion of accurate aneroid manometers appeared to be related to maintenance procedures. Aneroid sphygmomanometers must be calibrated periodically against a mercury manometer standard with a simple Y-tube connection. Only with careful observation, calibration, and maintenance should aneroid instruments be used in emergency care situations or in scientific studies concerned with indirect blood pressure.
Perlman LV, Chiang BN, Keller J, Blackburn H. Accuracy of Sphygmomanometers in Hospital Practice. Arch Intern Med. 1970;125(6):1000-1003. doi:10.1001/archinte.1970.00310060078007